On Passover eve, the Germans executed the final phase of the liquidation of the ghetto. The Germans planned for it to take three days. The Jewish armed underground consisted of two main groups: the ZOB, headed by Mordechai Anielewicz, which had no more than 800 fighters and the ZZW, headed by David Appelbaum and Pawel Frenkel, which had no more than 400 fighters. Most of the ZZW was lightly armed and, aside from Revisionists, it also contained some Bund and Agudat Israel (Orthodox) members. A few independent groups also existed which had a few hundred members. Despite pleas to the Polish underground to join, there was no help forthcoming from them. General Juergen Stroop attacked with an initial force of around 5,000 heavily armed troops, yet it took him weeks, even with tanks, artillery and air support, to crush the uprising.